Manufacture of waterproof and water-repellent noninflammable fibrous materials



Pagonted Mar. 15, 1949 MANUFACTURE OF WATERPROOF AND 'WATER-REPELLENTNONINFLAMMABLE FIBROUS MATERIALS Frederick F. Pollak, Brooklyn, andJosef Fassel,

Marmaroneck, N. X.

No Drawing. Application April 16, 1943, Serial No. 483,340

Claims. 1

The invention relates to the manufacture of waterproof andwater-repellent non-inflammable textiles and fabrics, and to substancesadapted to beused in connection with this manufacture.

In patent application Ser. No. 475,575 now- Patent No. 2,421,218, May27, 1947, a method is described for rendering textiles and fabrics notinflammable and water-resistant. These materials are impregnated with asolution of pycloudy surface appearance.

I the same in one bath.

fibre and its original pliability.

to avoid cloudy surface appearance.

in the incorporation of an insoluble melaminephosphoric acid compoundinto the fibre.

The method may be advantageously carried out by the impregnation of thetextiles and fabrics with a neutral pyrophosphoric acid salt of avolatile base, such as ammonia or a suitable amide or hydrazine, and-bypassing the dried or still moist materials through an aqueouscondensation solution of melamine and an aldehyde,

The pyrophosphoric acid salt may be directly If, however, this solutionis heated to about Ammonia hasbeen found to be highly useful The presentmethod may be advantageously It is advisable to remove sizing substancesThe processed fabrics or textiles are dried at The neutral ammonia saltof the pyrophos- The ammonia which is liberated at the elevatedtemperature reacts with the formaldehyde In view of the fact that 2 molsmelamine and 1 rophosphoric acid, thereafter passed through a such asformaldehyde. solution of a condensation product of melamine andformaldehyde, hardened and dried. An inadded to the condensationsolution which comsoluble melamine pyrophosphate is formed which mencesto be slightly cloudy after a long period is firmly embedded in thesynthetic resin coating. of standing only.

The method is satisfactory and efficient. However, two impregnatingsteps are needed for its 100 C., a white insoluble precipitate ofmelamine performance. The method also requires a rather and of thepyrophos-ph-oric acid is abruptly accurate control of the workingtemperature in formed. order to avoid weakening of the fibre during itsexposure to the acid solution. as a volatile base; but other suitablebases, such Furthermore, it has been observed that the as ethylenediamine, hydrazine or guanidine may precipitate sometimes does notsufiiciently penbe employed. etrate into the fibre which causes asomewhat carried out by using a. single impregnating bath It is theobject of the invention to improve containing all the substances formingthe inthe former method and to simplify and conduct soluble melamineprecipitate, through which the fabricsior textiles are passed. It is anobject of the invention to preserve the non-inflammability of theimpregnated textiles pr v y to h re m n and fabrics in spite ofintensive washing or long time exposure to water and to the atmosphere.a temperature of between 100 and 125 C. and

It is a further object of the invention to avoid preferably at about 120C. during the entire manufacturing procedure the The textiles andfabrics are hereby pr v d d contact of the fibres with acid solutions.with an impre and coa W ch rende s 11; is also an obje t of t inventiont fully the same non-inflammable, fireand water-proof preserve theoriginal mechanical strength of the and mildew-Proof, and which Cannotbe o d by Washing. Furthermore, it is an object of the invention toprocess colored goods without impairing in the phoric acid has beenfound to e particularly least their particular color, shade or tint, and40 useful in the performance of this invention- It is also an object ofthe invention to anchor the impregnating substances so firmly in the ifthe melamine condensation product, whereby cell structure of thetextiles and fabrics that gi g gfig gif ifggggg g fgg fs' i g g g gf fig gzl gg fif zfi g; fi gig gf s the formaldehyde is hereby torn from themelamine compound; hence, it follows that a preferthe original softtouch of thetreated materials. ably greater quantity of the condensationproduct With these and other ob ects in view which Should be employed asit would correspond to will become apparent as this specification prothet i h i tfl al relation. ceedathe invention comprises in its broadaspect the impregnation 0 fibrous m a s, Such as mol pyrophosphoric acidare required to form the particularly textiles and fabrics, with asolution compound and hexamethylenetetramine is proof/a melamie-aldehyde condensation product duced' from 3 mols formaldehyde and 2mols and a phosphoric acid salt of a volatile base, and

ammonia, it is desirable to have an excess of 3 formaldehyde in thecondensation bath as otherwise i'ree melamine would be produced.

Example I 126 parts by weight of melamine, 200 parts by weight offormaldehyde slightly alkalized by the addition of sodium-hydrate, arecondensed with 500 parts of water by heating the mixture for about 20minutes with a reflux cooler. The resuiting clear solution is cooled.

A concentrated solution containing 36 parts by weight of pyrophosphoricacid is neutralized by slowly adding to the same ammonia and cooling. Itis advisable to employ a small excess of ammonia so that the resultingsolution has a pH equal to about pH 7.5 which will prevent a prematureformation of the precipitate.

A fabric is passed through this impregnating solution in the customarymanner. The excess liquid is removed, for instance, by transporting theimpregnated article through wringer rolls. Hereafter the fabric is driedat a temperature of between 100 and 125 C. and preferably at about 120C. A water-insoluble melamine pyrophosphate is formed hereby which isfirmly em-.

bedded into the fibre. The fabric is preferably rinsed again with waterand dried. It is-now provided with the desired water resistance andwater repellent impregnation which cannot be removed by washingwithwater; At the same time it has been rendered non-inflammable andmildewproof.

The instant method may be performed by subjecting the textiles andfabrics to repeated impregnation in order to intensify its efiiciency orto obtain special effects. a

The relative quantities of the impregnating substances may be adjustedduring a first impreg nating phase in such a manner that no syntheticresin is produced, the formaldehyde and the melamine being used up intoto for the formation of the hexamethylenetetramine or themelaminepyrophosphate.

Hereafter a second impregnation may be conducted on the lines which aredescribed in Example I, the fabric after the first treatment being stillin a liquid absorbent state.

'A final product is hereby obtained which contains a considerably largerquantity of fibre-embedded melaminepyrophosphate without increase of theartificial resin.

A specific example of performing the invention in this manner is givenin the following:

Example II 126 parts by weight of melamine, 260 parts slightly alkalizedformaldehyde and 500 parts of water are condensated to form anartificial resin. A concentrated solution of 36 parts of pyrophosphoricacid is added which has been neutralized and slightly alkalized withammonia.

The fabric is passed through this solution and exposed to air forseveral hours. Hereafter it is conducted through the impregnating bathdescribed in Example I. The thus produced article has a superior waterrepellency.

The ammonia may be substituted by other amides the aqueous solutions ofwhich are alkaline. react with formaldehyde and form the desiredprecipitate at an elevated temperature.

Instead of the formaldehyde other aldehydes.

may be employed which by condensation with melamine form awater-insoluble colorless resin and are separable from the melaminecondensa- 4 tion product so that the insoluble melamine phosphoric acidcompound may be formed.

The fabric processed in accordance with the instant invention excels inpermanent non-infiammability which is not reduced if the articles arerinsed with water or located therein even for a longer period. The fibreis not weakened by the impregnation; it is water resistant and waterrepellent which greatly shortens the drying time.

The precipitate is formed within the cellular structure of theflbrewhich, therefore, remains unchanged at its surface. Consequently, darkcolored fabrics, such as uniform cloth, can be successfully treatedwithout necessitating an additional coloring procedure. The touch of thetextiles processed according to the invention is the fabrics retaintheir I food for their growth on the sterile coating.

The water resistance and repellency is ap-' parent from the fact thatthe processed fibres even if colored with a watersensitive dyestuif donot impart any dyestufl to water. If located in water for a long-periodthe water remains clear.

It was, found that at the same time the supershine of artificial sill:is eliminated which assumes the dull luster of first quality naturalsilk.

The invention may also be carried out by partly orcompletely'substituting the melamine formaldehyde condensation productby another hardenable synthetic resin. For instance, a mixture ofthiourea and melamine may be treated with formaldehyde and the mixedcondensation product may be incorporated into the fibre; either anexcess of formaldehyde may be employed, or the melamine condensationproduct may be substantially used up by the ammonium pyrophosphate orthe relative quantities maybe varied in another suitable manner.

The examples given above are not considered to be a limitation of theapplication or of the methods and products of the invention, becausevariations in percentages of the material used, in the timeandtemperature of the diiferent heating steps in the sequence thereof, inthe mode of application and in the use of the products of reaction canbe made by one skilled in the art to suit different requirements.

We claim:

1. A method of renderin textiles and fabrics, non-inflammable, waterandmildew-proof, comprising impregnating the said materials with an aqueoussolution of ammonium pyrophosphate and of a melamine-formaldehydecondensation product, drying the impregnated materials at an elevated.temperatureand incorporating thereby into the same, awater insolublemelamine pyrophosphate.

2. A method of rendering textiles and fabrics, non-inflammable, waterandmildew-proof, comprising impregnating the said materials with theaqueous solution of ammoniumpyrophosphate containing a slight excessquantity of ammonia, and of a melamine-formaldehyde condensationproduct, drying the impregnated materials at an elevated'temperature andincorporating thereby into the same a water insoluble melaminepyrophosphate.

8. A method of renderin textiles and fabrics, REFERENCES CITEDnon-inflammable, waterand mildew-proof, comprising impregnating th saimaterials ith th The following references are of record in the aqueoussolution of ammoniumpyrophosphate file Of this Patent? and of amelamine-formaldehyde condensation 5 'UNITED STATES PATENTS productcontaining a slight excess quantity of formaldehyde, drying theimpregnated materials Number Name Date at an elevated temperature andincorporating 2,097,509 9 2, 1937 thereby into the same a waterinsoluble melamine 2,161,803 FlPlayson et June 1939 pyrophggphatg .10 9,3 W1dmer ADI- 16, 1940 4. A method of rendering textiles and fabrics,2305035 Rqsser 1943 non-inflammable, Waterand mildew-proof, com-2,339,203 stleglel 11, 1944 prising impregnating the said materials withthe FOREIGN PATENTS aqueous solution of ammoniumpyrophosphate and of amelamine-formaldehyde condensation 15 Numlier Country. Date product, thelatter being maintained in the solu- Great ri m Apr. 29, 1936 tion in a,quantity slightly in excess to its stoich- 476,043 Great Bntain 1937eiometrical relation to the pyrophosphate. OTHER REFERENCES 5. A methodof rendering textiles and fabrics, non-infiammable,waterandmildew-proof, com- 20 g i ff b :32: igg chem prisin impregnating thesaid materials with a e pages slightly alkaline aqueous solution ofammoniumpyrophosphate and of a melamine-formaldehyde condensationproduct, drying the impregnated materials at a temperature of about 120C., and 5 again washing and drying the said materials.

FREDERICK F. POLLAK. JOSEF FASSEL.

